JPS59140103A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To suppress the road noise to the min. and improve the noise suppressing performance, residence performance, etc. by constituting the characteristics of the tread rubber for pneumatic tire so that the relation between the dynamic modulus and the loss tangent fulfills a specific equation. CONSTITUTION:The characteristics of the tread rubber for pneumatic tire is constituted so that the relation between the dynamic modulus E*(kgf/cm<2>) and the loss tangent tandelta fulfills the equation E*Xtandelta=20-70. The preferable state is constituted when the ratio (a) between E* and tandelta fulfills the equation (a)= E*/tandelta=100-350. The dynamic modulus E* taking account of viscoelastic properties is suitably adopted, when the hardness of a tire on traveling is discussed, with the representative value of vibration in the case when the minute unevenness of a road deforms a tire tread as 20Hz. Further, the damping performance is represented by using the loss tangent tandelta as the ratio between the dynamic modulus and the loss modulus as described above.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire that has excellent noise performance and provides comfortable axle running performance.

Pneumatic tires for vehicles support the axle, change direction,
It is a component that has important functions such as transmitting force. On the other hand, it is difficult to generate redundant vibrations and noise caused by unevenness of various sizes on the road surface.
In addition, being loose is also important for vehicle width and comfort, and tires also play a major role in these matters. In particular, noise called rotor noise has become a problem in recent years as vehicles become lighter.

Road noise is a ``low'' noise that is generated inside the vehicle when driving on a road surface that has minute irregularities or continuous surfaces, such as a relatively rough paved road surface or a cracked paved road surface.
This will seriously impair the comfort of the axle.

Many studies have been published on ways to improve low noise performance by improving tires, but the reality is that they are still far from being practical. 4.If you think about the comb in the tire tread that is in direct contact with the road surface (which is said to have a large effect), r' AN INV
ESTIGATION OT;”THE CHARAC
TERISTIC8ANOCAUSE OF ROAD
NOISE IN VEi-LICLESJ
M, 1. R, A, 5E COND REPORT
No. 1961/6 The ones with good tan pink stickiness are good, and the trend rubbers are N, 1%, SB, R.
From 1.1. R indicates good. Moat “Automobile Technology J Vol, 34, No. 12, 1980”
``O-Noise and Tire Strength'' states that tires with lower com hardness are better. However, these documents discuss general trends, and in reality, they are not practical. In general, hardness and damping properties of tread combs are not independent factors but have a positive correlation, so it is not easy to provide a tread comb that is soft and has excellent tamping properties.

Therefore, the inventors of the present invention have focused on the fact that rotary noise can be minimized by selecting l-let rubber with flexibility and damping performance within a specific range, and have arrived at the present invention.

Therefore, an object of the present invention is to provide a pneumatic tire that has excellent noise performance and provides comfortable vehicle running performance.

That is, the present invention provides a pneumatic tire characterized in that the relationship between the dynamic modulus of elasticity E'' (Kgf/ctrl) and the loss tangent tan δ satisfies the following formula (1) in terms of the tread comb of the pneumatic tire. Its gist is as follows.

E X1anδ220~70 --- (1)
A preferred embodiment in the case of a trench is E''' [where the ratio a of 1δ also satisfies the following formula (2).

a-E/lan δ= 100~350 -...-
(2+ Below, the circumstances that led to the present invention will be explained in detail.

In the present invention, we focused on the tread comb (hereinafter simply referred to as E'') and the loss tangent 1a...δ (hereinafter simply referred to as tanδ) regarding road noise.As for hardness, minute irregularities on the road surface deform the tire tread. vibration (
Consider E'' with 201'lZ as a typical value, usually from 1 to 1000'''. JIS hardness etc. d. It is a static hardness, and is not appropriate when discussing the hardness of a tire while running; in such a case, a dynamic elastic modulus E1 that includes viscous properties is appropriate. The damping performance is the loss tangent fa expressed as the ratio of the dynamic modulus to the loss modulus.
nδ is used.

Here, both J5' and Fnδ were measured using a viscoelastic spectrometer at 20°C, 2011''', and an initial strain of 10
d11] with a dynamic strain of ±2%.

Hereinafter, the practical ranges of E and Lan δ of the tread rubber for reducing road noise for the pneumatic tire of the present invention will be explained with reference to drawings showing experimental results.

Figure 1 shows practical tread rubber and non-practical tread rubber.
This is a graph showing the relationship between tan δ and tan δ, with white circles indicating practical tread combs and black circles indicating impractical tread combs.

Originally, El and fan δ of a comb should be independent of each other, and the size of E″ and fan δ should exist arbitrarily, but for combs that are put into practical use, this cannot necessarily be said to be independent.Especially when camping As for the tread comb, as shown in FIG. 1, E゛)2 and 18+1δ tend to have a relatively positive correlation.

Previous 01 research has introduced that in order to reduce road noise, it is best to redden the cap tread rubber, which has a large effect, or to change the deviation to one with good tamping characteristics.However, as mentioned above, In the case of practical l red rubber, it is no longer possible to select E4 heavy dynamic hardness) and dance δ (dumb pink time) independently of each other (for example, A1 in Figure 1).Therefore, We have come to believe that there is an optimal combination of E'': and fan δ.

FIG. 2 is a graph showing the relationship between E' Roto noise is recorded in the center of the vehicle interior, at the same height as the driver's ears, and is expressed in 80 to 250 11Z band sum dB. In addition, the road surface where rotor noise is likely to occur and the vehicle width running speed are 40 Kn! /hr is the measured take.

As shown in FIG. 2, the sound pressure level of the rotor noise is E
It becomes smaller from the range of 'i'/cnt, 25 to 65
Kg'/crtI particularly shows a minimum value at 35 to 55 Kgf/, d, and the smaller the value of a, the better.

In this way, the minimum value occurs in the relationship between roto noise and E"X L]4δ because E"Xtan
When the value of δ is large, the damping effect due to tan δ causes E
This is because the magnitude of tread excitation increases by one level due to the increase in tread excitation, and if the value of E" it is conceivable that.

From the above, from Figures 1 and 2, the effect of pneumatic tires on road noise as l/sod rubber is when a is 1.
00 to 350 Kri f/cd, and E”×i, Inδ
is 20-70Kgf, /CII, among which a =
150-300, E''X tan δ-25-65
is preferable, and even more preferable is a2 150 to 200,
It can be seen that E X tan δ-35 to 55.

As described above, in the present invention, the product of E and t δ is 20 to 7.
Since it is a pneumatic tire with a rating of 0Kyf7.4, the vibration input from minute irregularities on the road surface and the attenuation of the human-powered vibrations suppress the generation of road noise the best and improve the vehicle's performance! It can improve noise performance and improve comfortable living and driving performance.

[Brief explanation of the drawing]

Figure 1 shows the dynamic elastic modulus E' and loss tangent coefficient δ of the tread rubber.
Fig. 2 is a graph showing the relationship between lid'×lan
It is a graph showing the relationship between δ and road noise sound pressure level. Agent: Patent Attorney Makoto Ogawa − Patent Attorney: Ken Noguchi Patent Attorney: Kazuhiko Shimo

Claims (1)

[Scope of Claims] 1. A pneumatic tire characterized in that, in the characteristics of the tread rubber of a pneumatic tire, the relationship between the dynamic elastic modulus E'' (Kgr/71) and the loss tangent compensation δ satisfies the following formula (1). E X l-]0 mouth δ 2 20~70
...... (1)2 Ratio a of dynamic elastic modulus E' (Kg (/cd) and loss tangent dance δ
The pneumatic tire according to claim 1, wherein: also satisfies the following formula (2). a = E"/lan δ = 100~350 - (2
)